Will the salt water eat at protective gel coating in a fiberglass pool?

No, salt water will not eat at the protective gel coating in a fiberglass pool. Fiberglass pools are typically coated with a clear gel coat that is made of polyester or vinyl. This gel coat is designed to protect the fiberglass pool from damage caused by water, chemicals, and UV radiation. Salt water does not contain any chemicals that can damage the gel coat, and it is actually less corrosive than freshwater. In fact, salt water pools are often easier to maintain than freshwater pools because they do not require the addition of chemicals to prevent algae growth.